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<TITLE>JavaScript Source Code 3000:  Calculators:  Prime Number</TITLE>
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<META NAME="date" CONTENT="2000-09-09">
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<META NAME="description" CONTENT="Enter a number and JavaScript can instantly tell you if it is a prime number or not.  I wish I had this little gem to help me in my math classes!">

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<!-- Begin
function calculate(form) {
var num=parseInt(form.number.value);
if (isNaN(num) || num < 0) {
form.result.value=(form.number.value + " is not a valid number!  Try again!");
}
if (num == 1 || num == 2) {
form.result.value=(num + " is prime!");
}
for (var i=2;i<num;i++) {
if (num % i == 0) {
var prime="yes";
form.result.value=(num + " is not prime.  It is divisible by " + i + ".");
break;
}
if (num % i != 0) var prime="no";
}
if (prime == "no") form.result.value=(num + " is prime!");
} 
// End -->
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Home</A> </b><img src="../img/arrow.gif" /img/arrow.gif" height=13 width=7 border=0 alt="}"> <b><A HREF="index.htm" /calculators/"><font color="#FF0000">Calculators</font></A> </b>
<img src="../img/arrow.gif" /img/arrow.gif" height=13 width=7 border=0 alt="}"> <FONT COLOR="#006666">Prime Number</FONT></b></FONT><BR>
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Enter a number and JavaScript can instantly tell you if it is a prime number or not.  I wish I had this little gem to help me in my math classes years ago!
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<form name=form>
<h2>Prime Number Calculator</h2><p>
Please enter a number:<br>
<input type=text name=number size=7>
<input type=button value="Calculate" onClick="calculate(this.form)">
<P>
<input type=text name=result size=45 value="">
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<tr><td BGCOLOR=yellow><font FACE="helvetica,arial,geneva"><b>JavaScript Source Code 3000:  Calculator:  Prime Number</b>
<p>Simply click inside the window below, use your cursor to highlight the script, and copy (type Control-c or Apple-c) the script into a new file in your text editor (such as Note Pad or Simple Text) and save (Control-s or Apple-s).  The script is yours!!!<br><br></font></td></tr>
<tr><td BGCOLOR=yellow ALIGN=CENTER>
<form NAME="copy">

<DIV align="center">
<input type=button value="Highlight All" onClick="javascript:this.form.txt.focus();this.form.txt.select();">&nbsp;&nbsp;&nbsp;&nbsp;
<INPUT TYPE="text" NAME="total" VALUE="Script Size:  0.88 KB  " size="24">
</DIV>

<textarea NAME="txt" ROWS=20 COLS=75 WRAP=VIRTUAL>

&lt;!-- TWO STEPS TO INSTALL PRIME NUMBER CALCULATOR:

   1.  Paste the coding into the HEAD of your HTML document
   2.  Put the last code into the BODY of your HTML document  --&gt;

&lt;!--  STEP ONE: Copy this code into the HEAD of your HTML document  --&gt;

&lt;SCRIPT LANGUAGE="JavaScript"&gt;

&lt;! &gt;
&lt;! &gt;

&lt;!-- Begin
function calculate(form) {
var num=parseInt(form.number.value);
if (isNaN(num) || num &lt; 0) {
form.result.value=(form.number.value + " is not a valid number!  Try again!");
}
if (num == 1 || num == 2) {
form.result.value=(num + " is prime!");
}
for (var i=2;i&lt;num;i++) {
if (num % i == 0) {
var prime="yes";
form.result.value=(num + " is not prime.  It is divisible by " + i + ".");
break;
}
if (num % i != 0) var prime="no";
}
if (prime == "no") form.result.value=(num + " is prime!");
} 
// End --&gt;
&lt;/SCRIPT&gt;
&lt;/HEAD&gt;

&lt;!--  STEP TWO: Copy this code into the BODY of your HTML document  --&gt;

&lt;center&gt;
&lt;form name=form&gt;
&lt;h2&gt;Prime Number Calculator&lt;/h2&gt;&lt;p&gt;
Please enter a number:&lt;br&gt;
&lt;input type=text name=number size=7&gt;
&lt;input type=button value="Calculate" onClick="calculate(this.form)"&gt;
&lt;P&gt;
&lt;input type=text name=result size=45 value=""&gt;
&lt;/form&gt;
&lt;/center&gt;

 

&lt;!-- Script Size:  0.88 KB  --&gt;</textarea><br><font FACE="helvetica,arial,geneva"></font></td></tr>

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